If you look on-line you will find all of Lovell's Montreal Directories from the 1840s onwards. I used it to trace two families who settled there from Scotland in 1907. Year by year you could trace their movements about the city and gradually their children appeared as they started work. It was almost like an annual census. It won't likely be of any help in contacting the family now, but, if you haven't seen it, it will help fill in a few blanks.
Graham.